Web cutting mechanism



Jan. 9, 1,940. l w, PLSHMAKER A 2,186,884

WEB CUTTING MECHANISM Filed June 22, y1938 2 Sheets-Sheet 1 Jan. 9, 1940. w. P. SHOMAKER 2,186,884

Filed June 22, 1938 2 Sheets-Sheet 2 Patented Jan. 9, 1940 UNITED STATES PATENT OFFICE Wesley P. Shomaker, Richmond, Va. Application June 22, 1938, Serial No. 215,255

, My invention consists in new and useful im-4 provements in a web cutting mechanism for use in continuous feed, power-operated machines, and is primarily directed kto a patch cutting device for severing from a web of transparent material, 'strips for application to' window-type envelopes. It is the object of my invention to provide a. stripl cutting mechanism of this type wherein a continuously fed web may be severed at intervals Without interrupting or obstructing the continuous feed of the web. j

Another object of thepresent invention resides in the structure and operation of the knife Wherebythe latter, after severing a patch or strip, is automatically tilted in the direction of travel of advancing edge of the web, after which said knife is slowly returned to normal position.

l A further object of my invention is to provide a cutting knife and operating cam arrangement whereby the knife is subjected to a minimum of shock and strain, thus prolonging the life and utility of the knife.

A still further object of my invention isto pro- Vide a web cutting mechanism including a horizontal stationary knife and a perpendicular mo-vable knife lmounted on arms adapted to swing in anarc, said movable knife lbeing provided with a secondary fulcrum and means co-acting therewith ,to compensate for the arcuate movement of said supporting arms, whereby the shearing action is maintained substantially perpendicular.

. 'With the above and other objects in view which will appear as the description proceeds, my inven- Ition resides in the novel vfeatures herein set forth, illustratedhin the accompanyingv drawings and more particularly pointed out in the appended 4Referring tothe drawings in which numerals of like characterdesignate similar parts throughout the several views,

Fig. 1 is a perspective view of my improved strip cutting mechanism, showing the knife and cams in non-cutting positions.

Fig. 2 is a transverse section of the same, showing a continuous web being fed through the mechanism, with the parts in the positions shown in Fig. 1.

Fig. 3 is a similar view showing the parts in cutting position, and

Fig. 4 is a fragmentary view similar to those just referred to but showing the knife in tilted position which immediately follows the cutting position.

In the drawings, I represents a base o-r block in lthe Webso as to prevent the curling up of the` 2 claims. (c1. 164-43) which is preferably inset a horizontal stationary knife 2 of any' suitablev metal. A reciprocating vknife 3 perpendicular to said stationary knife and adapted to cooperate therewith, is secured to a knife bar 4 by means of screws 5 or other suitable means, with its yfree cutting edge normally in line forshearing engagement with the 'cutting edge of the stationary' knife 2. The knife bar 4 is rotatable andfor this purpose may be mounted ,ony an axle or shaft ty which projects therefrom at both ends where it is supported by the free ends of pivoted` arms I and 8, the latter being in turn pivotallyrmounted on allongitudinally extending shaft or`v rod 9 carried by the'machine proper.

l .f On the knife bar II adjacent one end of the reciprocating knife 3, I provide astop plate Ill which extends a predetermined distance below the free edge of the knife`3and is adapted to normally abutthe cutting edge of the stationary knife 2 to Iinsure proper shearing alignment of the two As heretofore pointed out, the knife bar I isA AspringsV llfwhichtend to maintain the abutment each endfof the shaft 6, one end of each spring 7 being lixedfto theshaft and the other end engaging the; knife ba'r 4 'to cause a rotary tension thereon.

`Similar springs I2 may be employed on the shaft l9 `for normally lifting the arms `I and 8, to

maintain the knives 2 and 3 outof engagement.

A rotary shaft ,I3 operatively connectedin any suitable manner to the motive power of the ma- `'chir'1e"'proper extends longitudinally above thereciprocating knife bar 4 and carries a pair of cams I4 and I5, one adjacent each of the arms 'I and 8, said arms beingprovided with rollers 14a and I5a' arranged in line for engagement by the respec` tive cams. These cams are so designed and positioned on the shaft that the raised portion of cam I5 is preferably slightly in advance of the raised portion of cam I4, whereby upon the rotation of the shaft I3, the end of the reciprocating knife 3 adjacent the cam I5 cuts slightly in ad- Vance of the other end, thereby affecting a shearing action on the web. 'A

Intermediate the cams I4 and I5 on the shaft I3 I provide a tilting cam I6 adapted to cooperate with a roller I'l carried by an upwardly extending rsis arm I8 on the knife bar 4. It will be noted that the tilting cam I6 is timed with respect to the cams I4 and I5 so as to operate immediately upon the completion` of the cutting action of the knife to instantly tilt the knife 3 outwardly by rocking the cutter bar 4 on its shaft in opposition to the action of the springs II. The forward edge Ia of the cam I6 is abrupt to insure immediate action in tilting the knife 3, but the rear or trailing edge I6b of said cam very gradually recedes so as to retard the return of the knife 3 to normal position by the springs I I and thus prevent a sudden shock which would otherwise occur when the stop plate I0 contacts the forward edge of the stationary knife 2.

This patch cutting mechanism is installed adjacent the feed rolls (not shown) of the machine with which it is to be used, and the shaft I3 is operatively connected in any suitable manner to the motive power of the machine so as to operate in timed relation with the feed of the web W.

In operation, the web W is 'fed past the stationary knife 2 at any predetermined speed and as the shaft I3 rotates in the direction of the arrow (Figs. 2 and 3), the cams I4 and I5 intermittently cause the knife 3 to shear patches from the web, the springs I2 on the shaft 9 causing the return of theknife 3 after each cuttingoperation. Immediately upon the conclusion of each down-stroke 'of the knife 3, the `forward face Ia of the tilting cam I6 engages the roller I'I on the upwardly extending arm I8 which rotates the knife bar 4 vand tilts the knife 3 in a direction away from the stationary knife, 'thereby preventing the advancing edge of the lcontinuously fed web from curling up behind the knife 3. This operation takes place simultaneously with the lifting of the arms 'I .and 8 by the springs I2, and by the time the knife 3 has assumed its uppermost position, the operation of the tilting cam I6 and springs II has begun to Aslowly return the knife 3 to its normalposition Aready for the next down-stroke.

I As before stated, the contour of the trailing edge I'Gb of the `cam IB insures the gradual return of the knife 3 to normal position without'permitting a sudden shock when the stop plate I0 contacts the for- .insures a substantially perpendicular cutting action of the knife. In other words, the fact thatA the arms 'I and 8 are pivoted to the rod or shaft 9 would normally cause the knife bar and knife to describe an arc. However, with the knife bar pivoted or rotary on the ends of the arms 1 and 8 and the normal engagement of the stop plate I0 with the forward edge of the stationary knife 2, the arc described by the arms 'I and 8 is compensated for and the substantially perpendicular cutting operation of the knife 3 is insured, and locking or jamming of the movable knife against the stationary knife is prevented.

yFrom the foregoing it is believed that the construction and advantages of my improved web cutting mechanism may be readily understood by those skilled in the art without further description, it being borne in mind that numerous changes may be made in the details disclosed without departing from the spirit of my invention as set out in the following claims.

What I claimand desire to secure by Letters Patent is:

l. Web cutting mechanism including a stationary knife, a pair of arms pivotally mounted above said stationaryknife, a cross bar rotatably supported at the free ends of said arms, a shearing Vknife carried by said cross bar, spring means tending to normally maintain said -arms in raised position, rotatable cam meansfor intermittently depressing said arms and shearing knife against the tension of said spring means, to effect a shearing action with said stationary knife, a stop and guide abutment carried by-said cross bar adjacent one end of said shearing knife and extending beyond the cutting edge of the latter, means cooperating with said-cross bar for yieldably maintaining said abutment in engagement with the cutting edgeof said stationary-knife, whereby the arcuate movement of said pivoted arms is compensated for to maintain said shearing knife substantially perpendicular to said stationary knife during its downward movement, a second rotatable cam arranged intimed relation with said'rst'named cam means and operatively associated with said cross bar, for rapidlyv rotating the latter in a direction to tilt said movable rknife away from said stationary knife upon the completionl of each down-stroke, and `means on said second cam for retarding the return movement of said shearing vknife to prevent suddene jecting into the path of rotation of said second cam, for tilting and retardingthe return movement of said shearing knife.

WESLEY P. SHOMAKER. 

